Iridium-containing oxide, method for producing same and catalyst containing iridium-containing oxide

Abstract

An iridium-containing oxide having a total pore volume of 0.20 cm3/g or more, calculated by a BJH method from nitrogen adsorption/desorption isotherm measurement, and a pore distribution having an average pore diameter of 7.0 nm or more.

What is claimed is: 
     
         1 . An iridium-containing oxide having a total pore volume of 0.20 cm 3 /g or more, calculated by a BJH method from nitrogen adsorption/desorption isotherm measurement, and a pore distribution having an average pore diameter of 7.0 nm or more. 
     
     
         2 . The iridium-containing oxide according to  claim 1 , wherein the iridium-containing oxide has hysteresis in a region where a relative pressure (P/P 0 ) of a nitrogen adsorption/desorption isotherm is 0.7 to 0.95. 
     
     
         3 . The iridium-containing oxide according to  claim 1 , wherein the iridium-containing oxide has a BET specific surface area of 100 m 2 /g or more. 
     
     
         4 . The iridium-containing oxide according to  claim 1 , wherein the iridium-containing oxide is an iridium oxide or a composite oxide of iridium and an element whose oxide has a rutile type crystal structure, and the iridium oxide or the composite oxide has a rutile type crystal structure. 
     
     
         5 . A method for producing the iridium-containing oxide according to  claim 1 ,
 the method comprising:   a step A of (1) dispersing iridium nanoparticles or iridium hydroxide particles as a raw material in a medium to obtain a dispersion liquid or (2) dissolving an iridium compound as a raw material in a solvent to obtain a solution;   a step B of converting water into high-temperature and high-pressure water under high-temperature and high-pressure conditions of a heating temperature of 100° C. or higher and an applied pressure of 0.1 MPa or more; and   a step C of mixing the dispersion liquid or the solution obtained in the step A with the high-temperature and high-pressure water obtained in the step B.   
     
     
         6 . The method for producing the iridium-containing oxide according to  claim 5 , wherein in the step A, the solvent has a temperature of 15 to 30° C., and the iridium compound as the raw material is dissolved in the solvent. 
     
     
         7 . The method for producing the iridium-containing oxide according to  claim 5 , wherein the step B comprises any one of the steps of: (1) adding an oxidant that releases oxygen atoms to the water and then converting the water into the high-temperature and high-pressure water;
 (2) converting the water into the high-temperature and high-pressure water and then adding an oxidant that releases oxygen atoms to the high-temperature and high-pressure water, or (3) adding an oxidant that releases oxygen atoms to the water, then converting the water into the high-temperature and high-pressure water, and further adding an oxidant that releases oxygen atoms to the high-temperature and high-pressure water.   
     
     
         8 . A cation exchange membrane water electrolysis anode catalyst comprising the iridium-containing oxide according to  claim 1 . 
     
     
         9 . A reverse potential durability catalyst for cation exchange membrane fuel cell, comprising an electrode catalyst layer containing the iridium-containing oxide according to  claim 1 . 
     
     
         10 . The iridium-containing oxide according to  claim 2 , wherein the iridium-containing oxide has a BET specific surface area of 100 m 2 /g or more. 
     
     
         11 . The iridium-containing oxide according to  claim 2 , wherein the iridium-containing oxide is an iridium oxide or a composite oxide of iridium and an element whose oxide has a rutile type crystal structure, and the iridium oxide or the composite oxide has a rutile type crystal structure. 
     
     
         12 . The iridium-containing oxide according to  claim 3 , wherein the iridium-containing oxide is an iridium oxide or a composite oxide of iridium and an element whose oxide has a rutile type crystal structure, and the iridium oxide or the composite oxide has a rutile type crystal structure. 
     
     
         13 . The iridium-containing oxide according to  claim 10 , wherein the iridium-containing oxide is an iridium oxide or a composite oxide of iridium and an element whose oxide has a rutile type crystal structure, and the iridium oxide or the composite oxide has a rutile type crystal structure. 
     
     
         14 . The method for producing the iridium-containing oxide according to  claim 6 , wherein the step B comprises any one of the steps of: (1) adding an oxidant that releases oxygen atoms to the water and then converting the water into the high-temperature and high-pressure water; (2) converting the water into the high-temperature and high-pressure water and then adding an oxidant that releases oxygen atoms to the high-temperature and high-pressure water; or (3) adding an oxidant that releases oxygen atoms to the water, then converting the water into the high-temperature and high-pressure water, and further adding an oxidant that releases oxygen atoms to the high-temperature and high-pressure water.